/*
 * Copyright (c) Double Symmetry GmbH
 * Commercial use requires a license. See https://rntp.dev/pricing
 */

package com.doublesymmetry.trackplayer

import android.net.Uri
import androidx.media3.common.util.UnstableApi
import androidx.media3.datasource.DataSource
import androidx.media3.datasource.DataSpec
import androidx.media3.datasource.TransferListener
import com.doublesymmetry.trackplayer.models.MediaHeaders

/**
 * Wraps a [DataSource.Factory] (typically `DefaultHttpDataSource.Factory`) to
 * inject per-URI headers stored in [MediaHeaders]. This is the standard
 * ExoPlayer extension point for customizing HTTP requests.
 */
@UnstableApi
class HeaderInjectingDataSourceFactory(
  private val baseFactory: DataSource.Factory
) : DataSource.Factory {

  override fun createDataSource(): DataSource {
    val base = baseFactory.createDataSource()
    return HeaderInjectingDataSource(base)
  }

  // Forwards every DataSource member explicitly. Kotlin's `: DataSource by delegate`
  // only generates stubs for abstract members; Java `default` methods such as
  // `getResponseHeaders` resolve to the interface default (empty map) and never
  // reach the delegate. ProgressiveMediaPeriod consults that map for `icy-metaint`
  // to decide whether to install IcyDataSource, so dropping it breaks ICY
  // streams entirely (#2638).
  private class HeaderInjectingDataSource(
    private val delegate: DataSource
  ) : DataSource {

    override fun open(dataSpec: DataSpec): Long {
      val perItemHeaders = MediaHeaders.get(dataSpec.uri.toString())
      if (perItemHeaders != null) {
        // Per-item headers take precedence so callers can override headers
        // ExoPlayer injects itself (notably `Icy-MetaData: 1`).
        val merged = dataSpec.httpRequestHeaders + perItemHeaders
        val newSpec = dataSpec.buildUpon()
          .setHttpRequestHeaders(merged)
          .build()
        return delegate.open(newSpec)
      }
      return delegate.open(dataSpec)
    }

    override fun addTransferListener(transferListener: TransferListener) {
      delegate.addTransferListener(transferListener)
    }

    override fun getUri(): Uri? = delegate.uri

    override fun getResponseHeaders(): Map<String, List<String>> =
      delegate.responseHeaders

    override fun read(buffer: ByteArray, offset: Int, length: Int): Int =
      delegate.read(buffer, offset, length)

    override fun close() = delegate.close()
  }
}